How to Add a Windows Domain User to SQL Server as 'sysadmin'
USE master
GO
CREATE LOGIN [domain\username] FROM WINDOWS WITH DEFAULT_DATABASE = [Master]
GO
EXEC sp_addsrvrolemember @loginame=N'domain\username', @rolename=N'sysadmin'
GO
USE master
GO
CREATE LOGIN [domain\username] FROM WINDOWS WITH DEFAULT_DATABASE = [Master]
GO
EXEC sp_addsrvrolemember @loginame=N'domain\username', @rolename=N'sysadmin'
GO